Coating nozzle cleaning apparatus



S'. A. LOPENSKI ET AL COATING NOZZLE CLEANING APPARATUS Filed Aug. 27,195'.7

May 5, y1959 2,884,895

VIIIIIIIIIM ited States Patet 2,884,895 CGATNG NQZZLE CLEANING APPARATUSStanley A. Lopenski and Gordon E. Childs, Pompton Plains, NJ., assignorsto Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Penu- Sylvania Application August 27, 1957, Serial No.680,543 4 Claims. (Cl. 118--49.1)

The present invention relates to an automatic machine forelectrostatically coating incandescent-lamp envelopes and of the typeshown in application Serial No. 603,636, tiled August 13, 1956, lby S.A. Lopenski et al., now U. S. Patent No. 2,811,131, but, moreparticularly, it relates to an improved cleaning device for removing anyexcess powder from the coating-nozzle assembly and associated powderfeedconduits of such a machine after each coating operation.

Heretofore, a mechanical cleaning device has been employed to -removeany excess powder which may have accumulated in the coating-nozzleassembly, in the powder-feed conduits and in the powder-return conduitsof auch a machine. lf such a cleaning device is not utilized, the excesspowder has a tendency to form agglomerations in the coating conduits,which agglomerations are frequently picked up on the next coating cycleand deposited as such in the lamp envelope, thus impairing the qualityof the coating. The utilization of such a mechanical cleaning device inconnection with electrostatic-coating machines has heretofore beensubject to certain disadvantages. For example, each of the cleaningdevices which heretofore have been positioned at each of the coatingstations has been provided with a spring biased blow-back arm whichcarries a flexible air conduit connected to an air compressor and to adischarge port in the arm. When the heads which carry the lamp envelopesare in the coating station vand the nozzle assembly is inserted upwardlywithin the heads preparatory to coating an envelope, a pulley on thehead contacts the blow-back arm to hold it out of alignment with thecoating-nozzle assembly. As the pulley indexes with the head out of thecoating station and the coating nozzle assembly is retracted within thehead, an arm-biasing spring causes the arm and the discharge port toswing supposedly into alignment with the de pressed coating-nozzleassembly to permit a blast of air to drive any powder remaining in thecoating nozzle and associated feed and return conduits, back into theexpansion chamber and into the powder collector, respectively.

In order to operate such a cleaning device satisfactorily exactalignment of the port in the blow-back arm with respect to .thecoating-nozzle assembly must be achieved. Due to collection of thepowder and the absence of lubrication in the moving parts, the arm oftensticks and the desired alignment is not always obtained. Also, theabrasive effect of the powder and the head on the moving arm causes weartherein and thus requires frequent replacement thereof. In addition thiscontiguous mechanical cleaning device has heretofore interfered withadjustment of the height of the coating nozzle. Further, since thecoating-nozzle assembly must be lowered below the plane of the armbefore cleaning, cleaned and raised again after cleaning within theperiod of index (i.e. 3A of a second), the time available for thecleaning of the coating-nozzle assembly and vassociated powder conduitsis limited to a rather brief portion thereof. Also, because of the timeelement the vertical path of movement of the coating-nozzle assembly islimited.

It is the general object of the present invention to avoid and overcomethe foregoing and other diiliculties of and objections to the prior-artmachines by the provision of an improved device for cleaning thecoatingnozzle assembly and associated powder-feed conduits of a coatingmachine, which device has no mechanical moving parts in contact with thepowder, does not interfere with the nozzle-height adjustment, eliminatesthe requirement of accurate alignment of the cleaning device with thenozzle assembly and increases the time available for the cleaningoperation.

Another object of the present invention is the provision of a devicewhich provides better cleaning of the coating-nozzle assembly andpowder-feed conduits and reduces the cost of maintenance thereof.

The aforesaid objects of the invention, and other objects which willbecome apparent as the description proceeds are achieved |by providing adevice for cleaning the coating-nozzle assembly and associatedpowder-feed conduits of an electrostatic-coating machine which devicecomprises a pneumatic valve located in the powderfeed conduits andadapted by fluid pressure and an associated control means to remainclosed during the coating operation and open during the cleaningoperation and having means associated with the pneumatic valve forcreating a vacuum suction therein.

For a `better understanding of the invention reference should be had tothe accompanying drawings wherein like numerals of reference indicatesimilar parts throughout the several views and wherein:

Fig. 1 is a side-elevational view, partially in vertical section, of anenvelope-supporting head, coating-nozzle injector assembly andassociated silica-smoke generator disposed at a coating station of anelectrostatic silicacoating machine and showing the associated cleaningdevice of the present invention in the closed or inoperative position.

Fig. 2 is an enlarged fragmentary vertical-sectional View of thecoating-nozzle assembly, coating tube and coating sleeve of thecoating-nozzle injector assembly.

Fig. 3 is a vertical-sectional View of the pneumatic valve associatedwith the cleaning device of the present rinvention and showing the valvein the open position.

Although the principles of the invention are broadly applicable toautomatic apparatus for the deposition of any nely-divided powder onarticles, the invention is particularly adapted for use in conjunctionwith the deposition of silica powder on incandescent-lamp envelopes andhence it has been so illustrated and will be so described.

With specific reference to the form of the invention illustrated in thedrawings and, referring particularly to Fig. l, an envelope-supportinghead of a machine for electrostatically coating incandescent-lampenvelopes 11 and of the type shown in the above-mentioned application,Serial No. 603,636, is indicated by the reference numeral 10. Since thehead 10 and associated burner l2, vnozzle-injector assembly 14 andsilica-smoke generator 15 of the machine are conventional and per se,form no part of the present invention, it is deemed suicient to onlybriefly describe their structure and operation.

The head 10 comprises a hollow body portion 16 rotatably mounted in achain conveyor 17 and provided with a chuck 18 contoured to receive andsupport the neck portion of an incandescent-lamp envelope 11. To providesupport means for the conveyor 17, as it is indexed with the heads 16from work station to work station by a conventional mechanism (notshown), Arollers 22 carried thereby ride on a stationary table 24 of themachine. In order to rotate the head and hence the lamp envelope 11during the silica-coating operation, a pulley 26 is adixed to the bottomof the body portion 16 and is driven by means of a belt 27. l

To provide support means for a powder-return sleeve 28 and a concentricinner powder-feed tube 30, a'bridge 32 aixed to such sleeve 28 and itsintegral tube 30 is reciprocably mounted on guides 42 (only one of whichis shown in Fig. 1) a'ixed to the frame portions 44 of the machine by aconventional connecting linkage (not shown) and a cam (not shown) on amain cam shaft 46 of the machine, thereby reciprocating a nozzleassembly carried by the tube 30 between the dotted line position and thesolid line position shown in Fig. 1. This nozzle assembly, as shown morein detail in Fig. 2, cornprises a nozzle 34, provided with a pluralityof coating outlets 36 and a probe 38, which projects axially from thenozzle 34, and is threadably connected thereto.

The silica-smoke generator comprises a reservoir 50 to which a quantityof silica powder 52 is fed through an inlet line 51 and in which thepowder is continually agitated toward an outlet 54 in the bottom thereofby a paddle 56 driven continuously by a motor 58. To provide means ofextracting the silica powder 52 through the outlet 54 dry high-pressureair is fed from an air supply (not shown) through a valve 60, controlledby a solenoid 62 in a coating circuit and through a constricted orificein a venturi 64 thereby producing a partial vacuum in the latter whichpicks up silica from the outlet 54 by suction to form silica smoke. Thissilica smoke is forced through a tube 66 into the reservoir 50 andagainst a target 68 positioned therein where agglomerates are broken up.The finely-divided particles of silica smoke are then forced by theair-pressure through a powder-feed conduit 70 extending through a Tconnection 71 to the above-mentioned powder-feed tube 30 and thencethrough the tube 30 and the nozzle 34, when the latter is in thesolid-line position shown in Fig. 1, and into the lamp envelope 11. Asshown in Fig. 1 the T connection 71 is connected by a conduit 72 to apneumatic valve 73 of the cleaning device of the present invention,which valve 73 is closed by fluid pressure during the coating operationand opened by closure of a cleaning circuit to cause operation ofcontrol means associated with the valve 73 during the cleaningoperation, as hereinafter explained in detail.

This coating circuit includes a conductor 74 extending from one side ofa voltage supply, indicated generally by the legend A.C. supply, to oneside of the coil of the solenoid 62, with such circuit then extendingfrom the other side of said coil through a conductor 75 to a contact 76of a microswitch 77, the operating arm 78 of which is controlled by acam 80 on the main cam shaft 46 of the machine. This circuit iscompleted by a conductor 82 extending from the operating arm 78 to theother side of the A.C. supply. When the cam 80 moves the operating arm78 into engagement with the contact 76, thereby closing the coatingcircuit and energizing the coil of the solenoid 62, the latter opens thevalve 60 to admit dry high-pressure air to the venturi 64 and begin theabove-'described coating operation.

After the coating of the envelope 11 has been completed, the cam `80will then have rotated suciently to open the coating circuit and thenmoving the operating arm 78 of the switch 77 into engagement withanother switch contact 84 in the cleaning circuit, thus interrupting thecoating circuit and causing deenergization of the solenoid 62, withattendant closure of the valve 60 and resultant cessation of the feedingof the silica powder to the nozzle assembly and the lamp envelope 11.

This cleaning circuit comprises a conductor 86 which extends from ajunction point with the line voltage conductor 74 to one side of a coil88 of a solenoid, the armature 90 of which is pivotably connected to astem 92 of a two-way valve 94 and which armature 90 is normally biasedto the left, as viewed in Fig. 1, by a spring 98. This cleaning circuitis then completed by a conductor which extends from the other side ofthe coil 88 to the contact 84, the operating arm 78 and the linevoltageconductor 82. It will also be noted that the coil of a second solenoid101 is connected to the conductors 86 and 100 and hence in parallel withsolenoid 88.

During the coating operation when the cleaning circuit is not energized,high-pressure air from an air supply (not shown) is supplied through aconduit 103 and a branch circuit 106 and the two-way valve 94 to aninlet conduit 107 for a housing 108 of the pneumatic valve 73. Thishousing 108 is connected by a conduit 110 to a venturi to whichhigh-pressure airis supplied through conduit 103 and a valve 104operated by the solenoid 101. At this time the solenoid-operated valve104 in conduit 103 is closed so that no high-pressure air enters theventuri 105 from the conduit 103.

Energization of this cleaning circuit causes simultaneous energizationof the coil 88 and the coil of the solenoid 101. Such energization ofthe coil 88 moves the armature 90 to the right, as viewed in Fig. l,thereby turning the valve stem 92 counterclockwise from the solidlineposition shown in Fig. 1 to the dotted-line position shown therein, thusclosing valve 94 to block the supply of high-presure air to thepneumatic valve 73 and opening the latter to the atmosphere whichaccordingly places this valve 73 in the solid-line position shown inFig. 3. Such energization of the coil of the solenoid 101 opens thevalve 104 and thus permits the ow of high-pressure air to the venturi105.

Pneumatic valve The operating means of the pneumatic valve 73 (Figs. 1and 3) comprises a resilient member 112, which extends slightly beyondthe outwardly-diverging beveled end-portions 114 of the housing 108, andis held in hermetic engagement therewith by means of sealing members116, each of which is adjustably secured to a anged portion 117 of thehousing 108 by means of bolts 113. As shown in Fig. 3, these sealingmembers 116 may be threadably connected to the conduits and 72respective.

Thus, during the coating operation when the two-Way valve 94 is in thesolid-line position shown in Fig. l, the high-pressure air admittedthrough the conduits 103 and 106, valve 94, and the inlet conduit 107 tothe housing 108, compresses the resilient member 112 thereby stretchingthe latter and causing it to collapse, from the solidline position shownin Fig. 3 to the dotted-line position shown in Figs. l and 3, with theattendant closure of the pneumatic valve 73 and the resultant preventionof movement of the silica smoke through the line 72 to the pneumaticvalve 73. However, when the coating circuit is interrupted by operationof the cam 80 and the cleaning circuit is closed thereby, this causesthe simultaneous energization of the coil 8S and the coil of thesolenoid 101 with the resultant cnt-cfrr of the high-pressure air to thehousing 108 and the opening of valve 104 so that such high-pressure airis now supplied to the venturi 185. The resilient member 112 thenretracts from its collapsed dotted-line position shown in Figs. l and 3,and returns to its normal solid-line position shown in Fig. 3, thusenabling the rush of the high-pressure air through a constricted orificein the venturi 10S to create a partial vacuum within the nozzle assembly(Fig. 2), powder-feed tube 30, powder-feed conduit 70, conduit 72, valve73 and conduit 110, and to remove by suction any excess powder thereinand to deposit it in a powder collector (not shown). It will beunderstood that a powder-return line 120 (Fig. 1) extending from thepowder-return sleeve 28 to the powder collector (not shown) andconnected to a vacuum source (not shown) cooperates with theabove-described cleaning device of the present invention to cause thecontinuing removal of excess silica powder from the powder-return sleeve28 and the powder-return line 120.

The cleaning device of the present invention is operative from the timethe coating circuit is deenergized by movement of the operating arm 78away from the contact 76 until it is again energized by return of theoperating arm 78 of the switch 77 into engagement with the contact 76,which period of time is substantially greater than the entire period ofindex of the machine. During the period of time in which the coatingcircuit is deenergized, the nozzle-injector assembly is retracted (i.e.moved downwardly) from the solid-line position shown in Fig. l to thedotted-line position shown therein, to permit the indexing of the headand the now coated envelope 11 out of the coating station and into thenext work station. While the nozzle injector assembly is in the loweredposition an adjacent head 10, supporting an uncoated envelope 11,indexes into the coating station whereupon the nozzle-injector assemblyis elevated into this now indexed head and envelope 11 to be coated, andthe above-described cycle of operation is repeated by opening of thecleaning circuit and closure of the coating circuit by engagement of theoperating arm 78 with the contact 76 of the switch 77.

It will be recognized by those skilled in the art that the objects ofthe present invention have been achieved by the provision of a cleaningdevice for a machine for electrostatically silica-coatingincandescent-lamp envelopes, which cleaning device has no mechanicalmoving parts in contact with the silica powder, and since it is notcontiguous to the coating-nozzle assembly does not interfere with thenozzle height adjustment. In addition, the cleaning device need not beaccurately aligned with the coating-nozzle assembly for ecient operationduring the cleaning operation. Further, by increasing the time availablefor the cleaning operation the cleaning device provides better cleaningof the coating-nozzle assembly and the associated powder-feed conduitsthereby reducing the cost of maintenance of the latter.

While in accordance with the patent statutes one best known embodimentof the invention has been illustrated and described in detail, it is tobe particularly understood that the invention is not limited thereto orthereby.

We claim:

1. A device for removing any excess powder from the coating-nozzleassembly and associated powder-feed conduits of a machine forelectrostatically coating lamp envelopes, comprising a valve connectedto said powder-feed conduits and adapted to be closed by fluid pressureduring the coating of said lamp envelopes by said machine, said valvebeing further adapted to be opened by the removal of said Huid pressurewhen the coating of said lamp envelopes has been interrupted, and meansconnected by operation of said valve to said coating-nozzle assembly andpowder-feed conduits and operable to remove any excess powder from saidcoating nozzle assembly and powder feed conduits.

2. A device for removing any excess powder from the coating-nozzleassembly and associated powder-feed conduits of a machine forelectrostatically coating lamp envelopes, comprising a valve connectedto said powderfeed conduits, control means operatively associated withsaid valve and operable to close said valve by uid pressure during thecoating of said lamp envelopes by said machine, said control means beingfurther operable to open said valve by removal of said fluid pressurefrom said valve when the coating of said lamp envelopes is interrupted,and vacuum-suction means connected by operation of said valve to saidcoating-nozzle assembly and powder-feed conduits and operable to createa partial vacuum in said coating-nozzle assembly, powder-feed conduitsand said valve when said valve is open for removing by suction anyexcess powder therefrom.

3. A device for removing any excess powder from the coating-nozzleassembly and associated powder-feed conduits of a machine forelectrostatically coating lamp envelopes, comprising a housing connectedto said powderfeed conduits, a hollow resilient member inatmospheresealing engagement with said housing, control meansoperatively associated With said housing and operable to introduce tluidpressure into said housing during the coating of said lamp envelopes bysaid machine and thereby cause said resilient member to collapsetogether, said control means being further operable to remove said iluidpressure from said housing when the coating of said lamp envelopes isinterrupted and thus cause said resilient member to open, andvacuum-suction means connected to said coating-nozzle assembly andpowderfeed conduits by said resilient member when the latter is open andoperable then to create a partial vacuum in said coating-nozzleassembly, powder-feed conduits and said resilient member for removing bysuction any excess powder therefrom.

4. A device for removing any excess powder from the coating-nozzleassembly and associated powder-feed conduits of a machine forelectrostatically coating lamp envelopes, comprising a housing connectedto said conduits, a hollow resilient member within said housing, sealingmeans for securing said resilient member in atmos phere-sealingengagement with said housing, control means operatively associated withsaid housing and operable to introduce iluid pressure into said housingduring the coating of said lamp envelopes by said machine and therebycause said resilient member to collapse together, said control meansbeing further operable to remove said fluid pressure from said housingwhen the coating of said lamp envelopes is interrupted and thus causesaid resilient member to open, and vacuum-suction means connected tosaid coating-nozzle assembly and powder-feed conduits yby said resilientmember when the latter is open and operable then to create a partialvacuum in said coatingnozzle assembly, powder-feed conduits and saidresilient member for removing by suction any excess powder therefrom.

References Cited in the tile of this patent UNITED STATES PATENTS2,633,154 Eastman Mar. 3l, 1953 2,641,282 Hallett June 9, 1953 2,811,131Lopenski Oct. 29, 1957

